One mode of insulin infusion treatment includes infusion pump therapy via a catheter, needle or other type of cannula. Infusion pumps offer the advantages of continuous infusion of insulin, precision dosing, and programmable delivery schedules. Together, these advantages result in more accurate blood glucose control. In this mode of insulin infusion treatment, the infusion pump remains attached to the user and required doses of insulin are delivered to the user via the pump.
One type of cannula is a catheter, which generally is a tube that can be inserted into the body to permit the administration of fluids. In infusion pump therapy, the types and sizes of the catheter may vary, but generally, the catheter is a thin, flexible tube. In some uses, however, it may be larger and/or rigid. A rigid, hollow, metal needle may also be used in place of a soft plastic catheter.
One type of conventional infusion set is sold as the Quick-Set® infusion set by Medtronic. In such devices, the infusion pump includes a catheter assembly connected to a pump via a tubing set, and a separate insertion device inserts and/or attaches the catheter assembly into/to a user via an introducer needle provided as part of the infusion set. The infusion set and insertion device can also be combined, as in the Mio® infusion set sold by Medtronic, which is an “all-in-one” design that combines the infusion set and insertion device into one unit.
Another type of insulin infusion device, known as a “patch pump,” has recently become available. Unlike a conventional infusion pump, a patch pump is an integrated device that combines most or all of the fluid components in a single housing that is adhesively attached to an infusion site, and does not require the use of a separate infusion (tubing) set. A patch pump adheres to the skin, contains insulin (or other medication), and delivers the drug over a period of time, either transdermally, or via an integrated subcutaneous mini-catheter. Some patch pumps communicate with a separate controller device wirelessly (such as one sold under the brand name OmniPod®), while others are completely self-contained.
A conventional infusion device can include a fluid connector, which may be releasably attached to a base that can be secured to a user's skin. An infusion pump supplies fluid to a catheter via the fluid connector/base engagement.
With such devices, however, there are concerns over the difficulty of balancing the force required to disconnect the tubing without pulling the catheter from the user's skin versus having enough retention force to secure the infusion components for everyday infusion. Another concern is that there may be a need to design a rotational lock between the fluid connector and the base. Yet another concern is that the separation force needs to be designed such that if a user accidentally snags the extension tubing on an external structure (e.g., a doorknob), the extension tubing will disconnect from the fluid connector without removing the catheter from the user's skin, thus saving the patient from the need to obtain, connect and re-insert a new infusion set.
Additionally, to protect the cannula and/or introducer needle prior to insertion, conventional devices often include a needle guard that is removed prior to use. These needle guards, however, are often very small and may be difficult to grasp, particularly for people with impaired dexterity. Additionally, conventional needle guards are often held in place by friction alone. To remove such needle guards, patients must pull and/or twist the needle guard, and the axial force required to remove such needle guards may vary widely, for example, based on manufacturing tolerances. Further, with such needle guards, once the coefficient of static friction is overcome, the guard may separate quickly, without providing an opportunity for a user to modify the applied force and potentially resulting in a needle-stick injury. Further, there is a risk that the needle guard can contact the needle during removal, potentially dulling the cannula or introducer needle.